Why websites block temporary email
If a form says your email is “not allowed”, “invalid”, or “not supported”, the site is most likely checking it against a list of temporary email domains.
Why sites do it
- Free trials and promotions. Without blocking, one person could claim the same offer many times.
- Spam and fake accounts. Throwaway addresses make it cheap to create accounts in bulk.
- Account recovery. A site knows a temporary inbox won’t be there when you need a password reset, and wants to avoid support tickets.
- Marketing. Some sites want an address they can keep emailing.
How the blocking works
Most sites check the part after the @ against a blocklist. Public lists of disposable email domains are maintained on the web and updated as new services appear. Some sites go further: they check how new a domain is, look up its mail servers, or use paid services that score each address.
Blocking can happen at two points. The form may reject the address straight away, or it may accept it and quietly never send the email. The second kind is why a code sometimes just never arrives.
When blocklists get it wrong
Blocklists aren’t perfect. Small email providers, new company domains, and privacy-focused forwarding services sometimes end up on them by mistake. If your real, permanent email is rejected, contact the site’s support and ask them to check it.
What you can do
- Accept the site’s decision. Getting around a block is against our acceptable use policy and usually the site’s terms.
- If you still want to keep the site out of your real inbox, use an email alias from your email provider or a forwarding service. Aliases vs disposable email explains how.
- Unsubscribe later, or filter the site’s emails into a folder.
For website owners
If you’re deciding whether to block temporary email, think about what you are protecting. Blocking makes sense for free trials and anything with money or reputation attached. For newsletters, downloads, and comment forms, blocking mostly turns away privacy-minded visitors who were never going to read your marketing anyway.